On New Year’s Eve mom called to say “Hi” and see what we were getting up to for the evening. She then told me the fireplace was working again. She hadn’t told me it wasn’t working, so I asked her about the problem. She said the inversion layer during the prior two days had been such that when she built and lit her fire, which she described in exacting detail, the house filled up with smoke. Yes, we did have several days of very high pressure over our region, however, the barometric pressure Can’t get high enough to drive smoke from the fireplace into the house unyieldingly. Wind, yes. An inversion layer, No. I’m sure she finally remembered to open the flue on her chimney.